<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>jQuery快速入门</title>
    <script src="/js/jquery-3.3.1.min.js"></script>
<script type="text/javascript">
    $(function () {
        $("#myinput").val("想你了")

         var value = $("#myinput").val();
         alert(value)
    })
</script>
<body>
<input id="myinput" type="text" name="username" value="想你"/><br>
<div id="mydiv"><p><a href="#">标签标题</a> </p></div>
</body>
</html>